we have some sections of the admin menu that lead to landing pages that list everything in that section. On pages like /admin and /admin/config this is particularly useful. But if there were only a single link on that landing page, it could be frustrating to click there, then need to click a level deeper immediately.
Search, for example, has only a single sub-page in core.

Content has only a single sub-page in core.

Administration also has only a single sub-page in core.

I'm not sure how hard it would be to do, but I would love it if when there is only a single sub-item it went directly to that section.
Recent comments
There is also Node Comments Search - this searches the node and all comments (default search is node and first page of comments) as part of the content search. Izzy's module above is a separate...
Search does not include comments
I have created a new module comment_search
Search does not include comments
If there is no response, alternatively, you can use a View with a list of comments, with a filter based on the comment text. I haven't tried it myself, I just got an idea.
Search does not include comments